This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We continue to conduct research at our permanent field site in the Ivory Coast's Tai National Park. Due to lingering socio-political unrest in Ivory Coast, maintaining our presence in the area has been challenging as the country continues to prepare for elections following a 2002 coup. Core support from Yerkes has been critical in this regards. During 2009, our field assistants continued to collect basic information on the behavioral ecology of the seven cercopithecid species ranging within the core study area of the Tai Monkey Project. These species are Colobus polykomos, Procolobus badius, P. verus, Cercopithecus diana, C. campbelli, C. petaurista and Cercocebus atys. Our emphasis has been on more detailed investigation into the ranging behavior, reproductive strategies and feeding ecology of the sooty mangabey group and field assistants followed the primary study group on a daily basis. Information on most aspects of diet, feeding and foraging behavior were collected on the approximately 115 members of the group, along with fecal samples for future assessment for SIV infection levels. We also began collecting material property data (hardness and toughness values) on mangabey foods in order to make inferences about the bony architecture of mangabey mandibles. Eventually, we intend to conduct similar studies on the colobine and guenon species at Tai using new field data and existing skeletal samples.